Dialkyl-substituted monoamidinium-templated oxalate-based noncentrosymmetric 2D compounds

1-Propyl-2-phenyl-3-methylamidinium (A) and 1-hexyl-2-phenyl-3-methylamidinium (B) cations are used to template the formation of two-dimensional (2D) oxalate-based bimetallic compounds of formula A[(MnCrIII)-Cr-II(C2O4)(3)] (1) and B[(MnCrIII)-Cr-II(C2O4)(3)] (2). The single-crystal X-rays diffraction analysis revealed that both compounds crystallize in noncentrosymmetric space groups. In both compounds, the bimetallic coordination network is made of slightly corrugated 2D (6,3) bimetallic honeycomb layers arranged in an eclipsed manner. The monocations are located between the layers without any preferential interaction with the anionic coordination network. The magnetic susceptibility measurements can be fitted using a Curie-Weiss law with Curie-Weiss temperatures of 9.9 K for 1 and 9.0 K for 2, revealing that the dominating exchange interaction is ferromagnetic. This favors the onset of a ferromagnetic long-range ordering at 6.0 K for 1 and 5.8 K for 2. (C) 2019 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.